Spinnerette closure for high pressure spinning of melt polymers



Jan. 24, 1967 a. w. STOCKBRIDGE I 3,299,470

SPINNERETTE CLOSURE FOR HIGH PRESSURE SPINNING OF MELT POLYMERS Filed Dec. 7,1964 2 Sheets-Sheet 1 BRUCE Wv STOCKBRIDGE INVENTOR.

A TTORNE Y5 Jan. 1967. B. w. STOCKBRIDGE 3,299,470

SPINNERETTE CLOSURE FOR HIGH PRESSURE SPINNING OF MELT POLYMERS Filed Dec. 7, 1964 2 Sheets-Sheet 2 BRUCE W. 8T0 CKBR/DGE INVENTOR.

United States Patent SPINNERETTE CLOSURE FOR HIGH PRESSURE SPINNING 0F MELT POLYMERS Bruce W. Stockbridge, Kingsport, Tenn., assignor to Eastman Kodak (Iompany, Rochester, N.Y., a corporation of New Jersey Filed Dec. 7, 1964, Ser. No. 416,460

4 Claims. (Cl. 18-8) This invention relates to spinnerettes adapted for the production of fibers from various melt spinning compositions such as polyamides, polyesters and the like in which the melt is extruded in the form of filaments under high pressure. More particularly, the invention relates to an improved spinnerette construction in which means are provided to secure the parts of the spinnerette assembly together by such construction and in such manner that when the spinnerette is connected to a supply of the melt spinning composition and the melt is forced through the spinnerette under high pressure the securing means, which is held under compression rather than under tension, can be much shorter in length than conventional securing means and thus subject to less distortion whereby leakage of the composition from the spinnerette assembly is effectively prevented.

As is well known, various types of man-made fibers can be produced from a wide variety of compositions which, in the form of a solution or a melt, are forced through a cup shaped stainless steel plate provided with a plurality of minute orifices and emerge therefrom in the form of continuous filaments. In the manufacture of certain types of fibers, such as those produced from cellulose esters, the composition employed is in the form of a solution of the ester in a volatile solvent which is forced through the spinnerette under relatively low pressures. In general no serious problems are encountered in providing a means for securing or holding the spinnerette parts together in a spinning assembly which is relatively leakproof, because the pressures employed in forcing such solutions through the spinnerette orifices are relatively low.

The conventional spinnerette assembly, for example, consists of a supply conduit in the form of a hollow cylindrical body threaded to a spinnerette holder which is generally in the form of a circular plate provided with a central passage for conveying the spinning solution or dope to a centrally disposed shallow distributing chamber. In such a construction there is secured to the spinnerette holder a circular clamp plate provided with a central orifice to accommodate the spinnerette proper, which is generally a thin stainless steel cup-shaped plate provided with a plurality of minute orifices. Superimposed on the spinnerette proper is a filter dress and support, the filter taking the form of a suitable cloth or metal fabric coextensive with a supporting frame or breaker plate provided with openings to permit free flow of the dope therethrough. Leakage of the spinning solution or dope from the assembly is prevented by providing suitable gaskets at points of metal-to-metal contacts. The clamp plate, together with the spinnerette and filter dress assembly, is secured to the spinnerette holder by means of a plurality of cap screws which passes through clearance holes in the spinnerette holder and are threaded into the clamp plate.

In normal operation, when the dope is forced through the assembly under pressure the cap screws holding the clamp plate to the spinnerette holder are under tension. In spinning filaments from solutions of cellulose esters such a construction works satisfactorily without leakage or deformation of the parts because the pressures are relatively low, i.e., of the order of 1,000-3,000 p.s.i. Howice ever, in a melt spinning operation, because of the relatively high viscosity of the spinning composition, much higher pressures are required to force the composition through the minute orifices of the spinnerette plate. Such pressures may run up to as much as 5,000 or even 10,000 p.s.i. depending upon the type of filtration required and on the viscosity characteristics of the melt. Under such circumstances it has been found that such extreme pressures result in a certain amount of elongation of the cap screws with the result that gasket seating pressures are no longer sufiicient to prevent leakage.

In high pressure melt spinning processes, such as those referred to above, leakage thus constitutes a serious problem which, in some cases may bring about conditions which require actual shutting down of the spinning operation altogether. For example, such leakage may result in a sufficient amount of exudation to cause the melt to drip from the spinnerette assembly onto the filaments being produced, with the result that numerous random blebs are formed in the filamentary product which renders it unfit for commercial use.

In some types of melt spinning, for example, it has been found advantageous, instead of employing the conventional circular construction of spinnerette assembly, to construct it in rectangular or obrund form. The obrund form of assembly is essentially rectangular except that at each end of the longer dimension the structure is in the form of a semi-circle, the diameter of which is equal to the width of the short dimension of the rectangle. However, as will be more fully set forth hereinafter, the improvement constituting the present invention is applicable to spinnerette assemblies of many different forms such as circular, elliptical, rectangular, obrund and others.

The present invention, accordingly, has as its principal object to provide an improvement in spinnerette assemblies which are particularly designed or adapted for the high pressure melt spinning of relatively viscous fiberforming compositions, whereby leakage of the melt spinning composition therefrom is effectively prevented.

A further object is to provide a spinnerette assembly which includes a spinnerette adapter or holder, a filter assembly, a spinnerette and a clamp plate, in which the spinnerette adapter is secured to the clamp plate by means which are under compression rather than tension when the assembly is employed for the melt spinning of viscous fiber-forming compositions under high pressures.

A still further object is to provide a means of minimizing the size of the elements by means of which the spinnerette adapter is secured to the clamp plate in a construction such as described in the preceding paragraph.

Other objects will appear hereinafter.

These objects are accomplished by the following invention which, in its broader aspects, comprises the provision of an improved spinnerette assembly made up essentially of a spinnerette adapter, a filter dress and its supporting means, a spinnerette and a clamp plate which is secured to the spinnerette adapter by means of a plurality of relatively short socketed set screws disposed in a plurality of holes centered at intervals along the parting line of the spinnerette adapter and the clamp plate, which screws, under conditions of use of the spinnerette assembly under high pressure melt spinning, are under compression and not tension as is the case with the cap screws customarily employed to hold spinnerette adapters and clamp plates together in the conventional spinnerette assemblies of the prior art.

In the drawings,

FIGURE 1 is a plan view of a conventional spinnerette assembly showing its supply conduit and the cap screws employed for securing a clamp plate to a spinnerette adapter.

FIGURE 2 is a vertical sectional view of a conventional spinnerette assembly illustrating the manner in which the spinnerette adapter, filter dress, spinnerette and gaskets are secured by the clamp plate.

FIGURE 3 is a plan view of the improved spinnerette assembly of the present invention showing the disposition of the securing elements and the retracting means employed for disassembling the device and also showing in dotted lines the internal distribution chambers and connecting channels as well as the polymer supply orifice.

FIGURE 4 is a vertical sectional view taken along the lines of 33 of FIGURE 3 and illustrating the manner in which the various elements of the improved structure are assembled.

FIGURE 5 is a vertical sectional view along the line 4-4 of FIGURE 3 also illustrating the manner in which the various elements of the improved structure are assembled and the manner in which the securing elements are disposed between the spinnerette adapter and the clamping plate and likewise showing how the retracting means are disposed between the spinnerette adapter and the clamping means.

In the following description there has been set forth several of the preferred embodiments of the invention but they are included merely for purposes of illustration and not as a limitation thereof.

The present invention can best be described by a comparison of its structural features with the corresponding structural features of spinnerette assemblies of the prior art as illustrated in FIGURES 1 and 2 of the drawings.

Referring to FIGURES l and 2, the numeral 1 designates a spinnerette adapter in the form of a circular steel plate which is provided with a central inlet aperture 2 and a centrally disposed internal chamber 3.

Numeral 4- designates a circular clamp plate provided with a central orifice to accommodate a flanged cup shaped stainless steel metal spinnerette 5 which is provided with a predetermined number of extrusion orifices or holes of very small diameter 6. Superimposed on spinnerette 5 is a filter dress 7 which may be in the form of a fabric woven from nylon or other suitable fibers or in the form of a metallic screen of relatively fine mesh. The filter dress 7 is supported by supporting members 8 and 9. The member 8 is in the form of a perforated metal disc, the perforations of which may be in the form of a cartwheel pattern. Member 9 is in the form of a perforated metal dome as shown, the perforations in both members 8 and 9 permitting free flow of the fiber-forming material through the spinnerette assembly.

Numeral 10 designates a plurality of cap screws passing through clearance holes 11 in spinnerette adapter 1 and threaded into tapped holes 12 in clamp plate 4.

Numeral 13 designates metal gaskets disposed above and below the filter dress, as shown, to prevent leakage of the spinning solution or dope from the assembly.

spinnerette adapter 1 is also provided with a suitable inlet conduit 14 threaded into adapter 1 as shown in FIGURE 2. Gasket 15 provides a seal against leakage of spinning solution from conduit 14.

In producing filaments with the device of FIGURE 2 a spinning solution (or melt) is conducted to the spinnerette assembly through conduit 14 under pressure. As discussed above, the pressures employed in the spinning of cellulose ester solutions are relatively low, as for exam le, 1,0003,000 p.s.i. However, when employing melt spinning compositions such as those made up of polyamide or polyester materials which have relatively high inherent viscosities, much higher pressures of the order of 5,000 psi. or more must be employed to force the melted spinning material through the filter and spinnerette orifices. When employing either type of fiber-forming material, however, it will be apparent that pressure is exerted uniformly within the distribution chamber 3 (as shown by the arrows) thus producing a force which tends to separate spinnerette adapter 1 and clamp plate 4. This separating force results in loading cap screws 10 in tension as indicated by the arrows applied to these elements as in FIGURE 2. Under moderate pressures this tension produces a minute amount of elongation of cap screws 10 but not enough to reduce gasket seating pressures to such an extent that leakage occurs. On the other hand, under the much higher pressures employed in melt spinning the amount of elongation of the cap screws is substantially increased with the result that gasket seating pressures are no longer sufficient to prevent leakage of the melt from the assembly. H

As indicated in the discussion of the objects of the invention, the principal objective is to provide a spinnerette assembly which is not subject to leakage of the fiber-forming material therefrom even under the high pressures employed in melt spinning, that is, a device in which gasket sealing pressures are not diminished during the spinning operation but are maintained at all times at a value sufiicient to prevent leakage. This result is obtained in the present invention by providing a spinnerette structure in which the clamp plate is secured to the spinnerette adapter by a plurality of set screws of special design and coaction with the spinnerette adapter and clamp plate in such manner that these securing elements are, in use, always under compression, rather than tension as are the cap screws of the prior art spinnerette structure described above. These features will be apparent from a consideration of one form of the improved structure of our invention as illustrated in FIGURES 3, 4 and 5 of the drawing.

Referring to FIGURE 4, the numeral 16 designates a spinnerette adapter provided with a central inlet aperture 17 through which a melt spinning composition under pressure passes through channels 18 and 19 to centrally disposed internal distribution chambers 20 and 21. If desired, a single distribution chamber coextensive with the lower face of the spinnerette adapter may be employed instead of the double chamber construction shown.

Spinnerette adapter 16 is secured to clamp plate 22 by means of a series of threaded socketed set screws or pins 23 disposed in a plurality of holes 24 centered on the parting line of the spinnerette adapter and the clamp plate as shown in FIGURE 3. In each case that half or portion of the hole falling within the clamp plate is provided with threads 25 while that portion falling within the spinnerette adapter has a smooth surface 25a and simply provides clearance for passage of the set screw 23. In assembling the parts each set screw 23 is threaded into its respective hole 24 and presses against a hardened steel thrust washer 26 which in turn presses against a shoulder 27 formed between the bottom and the smooth surface portion of the hole.

Clamp plate 22 is provided with an opening to accommodate a stainless steel metal spinnerette 28 in the form of a flat plate provided with a predetermined number of extrusion orifices or holes 29 of very small diameter. Superimposed on spinnerette 28 is a filter dress 30 which may be in the form of a fine wire mesh, a porous metal plate or other suitable filtering medium such as a body of sand or other appropriate filtering medium. Filter 30 is supported by an element 31 which may take the form of a coarse metallic screen which in turn is supported by a perforated steel breaker plate 32 of such thickness as to withstand the heavy pressures applied to the filter and supporting assembly by the viscous melt spin ning composition forced therethrough under high pressure.

Gaskets 33 and 34 are provided as shown in FIGURE 4 to prevent leakage of the spinning composition from the assembly. These gaskets may be of a relatively soft metal such as aluminum or copper and of such characteristics as to provide an effective seal when pressure is applied.

Referring to FIGURE 5 the letter P indicates pressure which is uniformly distributed within the distribution chambers 20 and 21 (as shown by the arrows) which produces a force which tends to separate spinnerette adapter 16 and clamp plate 22. Since the spinnerette adapter 16 and clamp plate 22 are secured together by set screws 23 as shown in FIGURES 4 and 5 no separation of these elements can take place. The forces acting on set screws 23 when pressure is applied by the incoming fiber-forming material in distribution chambers 20 and 21 are represented by arrows C and C and are compressive forces, rather than tension forces as in the case of the cap screws employed to hold together the spinnerette assembly of FIGURES l and 2. More specifically, it will be seen from FIGURES 4 and 5 that when pressure develops in either or both of distribution chambers 20 and 21 by the incoming molten fiber-forming composition, this pressure is transmitted to the underlying elements, namely, filter 30, screen 31, breaker plate 32 and spinnerette plate 28 and is also transmitted to clamp plate 22 since these elements are held in place by internal flange 34 of plate 22. The downward pressure or force just referred to is represented by C in FIGURE 5. At the same time the pressure P in chamber 21 also exerts an upward pressure or force C on spinnerette adapter 16 but sinceadapter 16 is held in place by set screws 23 there are two opposite forces acting on the set screws, namely, C and C. These are thus compressive forces with respect to set screws 23 rather than tension forces and while they may tend to produce a certain minute amount of shortening of these screws, the actual dimensional'change is very much less than is the case with the cap screws 10 of the prior art spinnerette assembly illustrated inFIGURE 2. In that'case the force acting on the cap screws, due tothe pressure exerted by the molten fiber-forming material entering distribution chamber 3 and transmitted through filter dress 7, supporting members 8 and 9 and spinnerette 5 to clamp plate 4, are exclusively tension forces which tend to and do lengthen cap screws 10. Since cap screws 10 are much longer than set screws 23 of the device illustrated in FIGURES 4 and 5 the total dimensional change in these cap screws is much larger and this has been found in practice to be sufficient to reduce gasket setting pressures in such an assembly to such an extent to cause leakage therefrom than is the case with the prior art spinnerette assembly of FIGURES land 2. Since, at a given level of stress the elongation or shortening of a fastener is proportional to its length, the shorter the fastener the smaller the change in its length. In other words, because the set screws employed in the present invention are so much i and the smooth surface portion of the hole.

shorter than the corresponding cap screws of the prior art device (assuming the two assemblies to be of comparable'dimensions), the total change in length of these securing elements due tostress is very much less than in the prior art asembly. The net result is that the gasket seating stress can by this means be maintained without leakage over a much wider range of pressures, when a viscous melt spinning composition is forced through the spinnerette under high pressures, than would be the case when employing a prior art assembly such as that shown in FIGURES 1 and 2.

One further point should be clarified and that is the matter of why that half of each circular opening 24 which falls within the spinnerette adapter is unthreaded while that portion of the opening falling within the clamp plate is threaded. If both portions of the openings or holes 24 were threaded there would be no clamping action of clamp plate 22 against spinnerette adapter 16 because there could be no relative movement between these two elements. Hence, when set screw 23 is turned down against thrust 6 washer 26, which in turn presses against shoulder 27 formed between the bottom and the smooth portion of the hole 24, clamp plate 22 and spinnerette adapter 16 must be movable in order to obtain the desired clamping action.

For purposes of disassembly, retracting set screws 35 are provided in a series of holes 37 also disposed along the parting line 22a between spinnerette adapter 16 and clamp plate 22 in the manner shown in FIGURE 5. In each case that portion of the hole falling within the spinnerette adapter plate 16 is provided with threads 38 while that portion falling within the clamp plate 22 has a smooth surface 38a and simply provides clearance for passage of the screws 35. In disassembling the parts each set screw 35 is threaded into its respective hole 37 and presses home against the hardened steel thrust washer 36 which in turn presses against a shoulder 39 formed between the bottom In this manner spinnerette adapter 16 may be extracted from the clamp plate 22, it being understood that each of the retracting screws 35 will be turned little by little in succession along the parting line 22a.

The action of the retracting screws 35 to lift and separate spinnerette adapter 16 from clamp plate 22 will be clarified by reference to the above description of the manner in which set screws 23 function to hold these parts clamped together. The openings for the retracting screws 35 are of exactly the same type as the openings for the set screws 23 except that they may be of smaller diameter and except that the threaded and smooth portions of each opening are reversed, that is, that portion of each opening which falls within the spinnerette adapter is'threaded while that portion which falls within the clamp plate is unthreaded, thus permitting spinnerette adapter 16 to be removed from clamp plate 22 by successively turning each of retracting screws 35. As one of these screws is turned it bears on thrust washer 36 which in turn presses against shoulder 39 formed be tween the bottom and the smooth surface of the hole and thus, with a sufiicient amount of turning of each of these retracting screws 35, separation of spinnerette adapter 16 from clamp plate 22 can be accomplished.

It will be understood that in use the spinnerette assembly is secured to a suitable source of melt spinning composition 40 shown in fragmented form and provided with a centrally disposed inlet passage 41 which connects with inlet aperture 17 of spinnerette adapter 16. Suitable sealing means such as gasket 42 provides a liquid seal. Spinnerette adapter 16 may be secured to supply element 40 by means of cap screws or other suitable securing means (not shown).

Reference has been made above to various shapes of spinnerette assemblies. It will be understood that the improved securing means of our invention is equally effective regardless of the shape of the assembly, that is, it may be applied with equal success to the round, elliptical, rectangular, obrund or other shapes of assemblies.

The advantage of securing the clamp plate to the spinnerette holder of a spinnerette assembly in accordance with the invention has been set forth above but it should be reemphasized that the principal advantage derives from the fact that the means for securing the clamp plate to the spinnerette holder, that is, the set screws or other equivalent securing means, being under compression rather than under tension, can be much shorter in length than the conventional cap screws or bolts employed in previously known devices. As previously pointed out, the shorter holding means are subject to less total distortion than the longer holding or securing means of the prior art devices and, as a result, under the extremely high pressures employed in melt spinning of fibers, the gasket sealing pressures can be maintained at all times at a sufiicient value to preclude escape of the melt from the assembly with its many attendant disadvantages.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

I claim:

1. In a spinnerette assembly adapted for producing filamentary material by extrusion in the form of filaments of a viscous molten fiber-forming composition under pressure, the combination of a spinnerette adapter provided with a centrally disposed inlet or feed channel for introduction of molten fiber-forming composition and having an internal centrally disposed distribution chamber therein communicating with said feed channel, a clamp plate secured to said adapter and having an opening therein to receive the adapter in close fitting but removal relationship thereto, said clamp plate having an internal flange on the inner surface of which is disposed a perforated spinnerette plate, a filter screen superimposed on said spinnerette plate and means for connecting a high pressure supply of molten fiber-forming composition to said adapter, said clamp having disposed around its inner periphery and in centered relation along the parting line between the spinnerette adapter and the clamp plate a plurality of threaded semi-circular openings adapted to receive threaded securing pins, a series of corresponding semi-circular unthreaded openings in the spinnerette holder of the same diameter as said first mentioned circular openings and also adapted to receive said securing pins, said securing pins being threaded into the threaded semi-circular openings in the clamp plate to secure said adapter, clamp plate, filter and spinnerette together but being freely movable along the surfaces of the unthreaded openings in the spinnerette adapter, said securing pins, upon application of internal pressure to the distribution chamber of the spinnerette adapter through the medium of the molten fiber-forming composition, being under compression, whereby leakage of fiber-forming composition from the assembly is prevented.

2. The spinnerette assembly of claim 1 having a re tracting means for separating the spinnerette adapter from the clamp plate, said retracting means comprising a plurality of circular openings disposed at intervals in centered relation along the parting line between the spinnerette adapter and the clamp plate, the portion of each opening which falls Within the adapter being threaded and the portion of each opening which falls within the clamp plate being unthreaded.

3. In a spinnerette assembly adapted for producing filamentary material by extrusion in the form of filaments of a viscous fiber-forming composition under pressure, the combination of spinnerette adapter means provided with an inlet or feed channel for introduction of molten fiberforming composition and having an internal distribution chamber therein communicating with said feed channel, clamp plate means secured to said spinnerette adapter means and having an opening therein to receive the adapter means in close fitting but removal relationship thereto, said clamp plate means having an internal flange means on the inner surface of which is disposed a perforated spinnerette plate, and means for connecting a high pressure supply of fiber-forming composition to said spinnerette adapter means, said clamp plate means having disposed around its inner periphery and in approximately centered relation along the parting line between the spinnerette adapter means and the clamp plate means a plurality of openings adapted to receive securing means, a series of corresponding openings in the spinnerette adapter means of the same diameter as said first mentioned circular openings and also adapted to receive said securing means, said securing means being positioned in said openings and engaged with the clamp plate to secure said adapter means, clamp plate means, and spinnerette together but being freely movable along the surfaces of the openings in the spinnerette adapter means, said securing means, upon application of internal pressure to the distribution chamber of the spinnerette adapter through the medium of the fiber-forming composition, being under compression, whereby leakage of fiber-forming composition from the assembly is prevented.

4. In a spinnerette assembly adapted for producing filamentary material by extrusion in the form of filaments of a viscous fiber-forming composition under pressure, the combination of spinnerette adapter means provided with an inlet or feed channel for introduction of fiber-forming composition and having an internal distribution chamber therein communicating with said feed channel, clamp plate means secured to said spinnerette adapter means and having an opening therein to receive the adapter means in close fitting but removal relationship thereto, said clamp plate means having internal seating means on the inner surface of which is disposed a perforated spinnerette plate, and means for connecting a high pressure supply of fiberforming composition to said spinnerette adapter means, said clamp plate means having disposed around its inner periphery and in approximate centered relation along the parting line between the spinnerette adapter means and the clamp plate means a plurality of grooved openings adapted to receive grooved securing means, a series of corresponding ungrooved openings in the spinnerette adapter means of the same diameter as said first mentioned openings and also adapted to receive said securing means, said grooved securing means being seated into the grooved openings in the clamp plate means to secure said adapter means, clamp plate means and spinnerette together but being freely movable along the surfaces of the ungrooved openings in the spinnerette adapter means, said grooved securing means, upon application of internal pressure to the distribution chamber of the spinnerette adapter means through the medium of the fiber-forming composition, being under compression, whereby leakage of fiber-forming composition from the assembly is prevented.

References Cited by the Examiner UNITED STATES PATENTS 2,784,843 3/1957 Braunlich. 2,892,675 6/1957 Bradshaw. 3,123,858 3/1964 McDermott 18 8 WILLIAM J. STEPHENSON, Primary Examiner. 

1. IN A SPINNERETTE ASSEMBLY ADAPTED FOR PRODUCING FILAMENTARY MATERIAL BY EXTRUSION IN THE FORM OF FILAMENTS OF A VISCOUS MOLTEN FIBER-FORMING COMPOSITION UNDER PRESSURE, THE COMBINATION OF A SPINNERETTE ADAPTER PROVIDED WITH A CENTRALLY DISPOSED INLET OR FEED CHANNEL FOR INTRODUCTION OF MOLTEN FIBER-FORMING COMPOSIITION AND HAVING AN INTERNAL CENTRALLY DISPOSED DISTRIBUTION CHAMBER THEREIN COMMUNICATING WITH SAID FEED CHANNEL, A CLAMP PLATE SECURED TO SAID ADAPTER AND HAVING AN OPENING THEREIN TO RECEIVE THE ADAPTER IN CLOSE FITTING BUT REMOVAL RELATIONSHIP THERETO, SAID CLAMP PLATE HAVING AN INTERNAL FLANGE ON THE INNER SURFACE OF WHICH IS DISPOSED A PERFORATED SPINNERETTE PLATE, A FILTER SCREEN SUPERIMPOSED ON SAID SPINNERETTE PLATE AND MEANS FOR CONNECTING A HIGH PRESSURE SUPPLY OF MOLTEN FIBER-FORMING COMPOSITION TO SAID ADAPTER, SAID CLAMP HAVING DISPOSED AROUND ITS INNER PERIPHERY AND IN CENTERED RELATION ALONG THE PARTING LINE BETWEEN THE SPINNERETTE ADAPTER AND THE CLAMP PLATE A PLURALITY OF THREADED SEMI-CIRCULAR OPENINGS ADAPTED TO RECEIVE THREADED SECURING PINS, A SERIES OF CORRESPONDING SEMI-CIRCULAR UNTHREADED OPENINGS IN THE SPINNERETTE HOLDER OF THE SAME DIAMETER AS SAID FIRST MENTIONED CIRCULAR OPENINGS AND ALSO ADAPTED TO RECEIVE SAID SECURING PINS, SAID SECURING PINS BEING THREADED INTO THE THREADED SEMI-CIRCULAR OPENINGS IN THE CLAMP PLATE TO SECURE SAID ADAPTER, CLAMP PLATE, FILTER AND SPINNERETTE TOGETHER BUT BEING FREELY MOVABLE ALONG THE SURFACES OF THE UNTHREADED OPENINGS IN THE SPINNERETTE ADAPTER, SAID SECURING PINS, UPON APPLICATION OF INTERNAL PRESSURE TO THE DISTRIBUTION CHAMBER OF THE SPINNERETTE ADAPTER THROUGH THE MEDIUM OF THE MOLTEN FIBER-FORMING COMPOSITION, BEING UNDER COMPRESSION, WHEREBY LEAKAGE OF FIBER-FORMING COMPOSITION FROM THE ASSEMBLY IS PREVENTED. 